Many commands for the jp profile family need a '-p' argument to pass the target profile.
jp profile delete, though, does not support.
I think we should be more consistent and add '-p' everywhere or nowhere.
What do you think ?

There are 2 reasons why -p is not used for "profile delete"
1) -p is here when a connection is needed (or a "plug" which is starting the profile session without connecting to the XMPP account), this is not necessary for a profile deletion
2) -p is optional, and default to "@DEFAULT@" (i.e. the default profile). For a deletion, it could lead to the accidental deletion of the default profile, so it is better to have a positional argument (which is mandatory) here.